The present invention relates generally to the field of textile printing apparatuses and, more particularly, to a multi-head, carousel-type textile printing apparatus in the mid-price range. The new printing apparatus has several unique structures for effecting head movement, printing, and rotational indexing and registration of the carousel and platens mounted thereon.
Previously, carousel-type textile printing machines for applying words and designs to fabric, such as T-shirts, jackets and the like generally fell into two categories: those which are highly automated, high-speed, and thus, very expensive, for example in the range of $30,000 to $80,000 for one machine; and those which are entirely manually operated. The latter of course operate much more slowly, allowing printing of perhaps two or three dozen pieces per hour, but are much less expensive to manufacture, and thus the cost is, for example, approximately $6,000 or $7,000.
Accordingly, a need exists in the marketplace for a multiple head textile printing apparatus in the mid-price range (approximately $12,000 to $17,000) for use in print shops of intermediate size which may wish to print quantities up to approximately 40 to 60 dozen pieces per hour with use of only a single machine without additional labor costs to produce the pieces.
To meet this need it is necessary that the multiple heads of the new carousel-type printing apparatus be automatically coordinated in their vertical action, as well as in their registration over the respective work pieces, so that multiple operators are not required to be positioned at all times at each of up to, for example, six or seven printing heads. Satisfying this need would avoid additional labor costs in producing each printed piece.
In order to keep the cost of manufacturing the apparatus and operating same to a minimum, it is also necessary that the flooding of the print screen with ink and printing therewith be as automated and efficient as possible, while still providing high quality, unsmudged prints, but in a mechanically simple manner.
A large portion of the expense involved in manufacturing fully automated multi-head carousel-type printers is involved in the structure for automatic rotational indexing and registration of the carousel carrying the printing platens. When the carousel stops it is especially important that each platen thereon be positioned in precise registration under a printing head so that the printed design will be properly aligned on the work piece.
Known printing machines have previously required time-consuming, and thus expensive manual adjustment for proper registration, resulting in a lower manufacturing cost; or alternatively, the machines were formed with complex and thus expensive equipment for automatic indexing and registration. The new textile printing apparatus described below is provided with a carousel which has both a relatively simple, inexpensive structure, and yet is capable of providing fast, precise registration between the printing head and the work piece platen.
For moving each of the multiple heads of a printing machine, known machines commonly employ a pneumtic lift cylinder for each head. These lift cylinders can be positioned in close proximity to the inner end of the printing head. Alternatively, the cylinders can be positioned at an opposite, outer end of the print head. The multiplicity of lift cylinders provides an additional source of substantial manufacturing expense. Further, the multiplicity of lift cylinders offers an increased chance of malfunction requiring maintenance cost. Finally, the multiplicity of lift cylinders makes precise coordination of simultaneously lifting and lowering all print heads more difficult. The new textile printing apparatus described below has a relatively simple structure which also allows for improved simultaneous lifting and lowering of all print heads. The simplified structure of the new textile printing apparatus also reduces the chances of malfunction of an individual print head in raising and lowering.
Different approaches to the actual step of printing have been used in the past. Highly automated machines often include a flood bar for spreading the ink and a "squeegee" for scraping excess ink from the print screen which are separately mounted on individual, parallel support bars. In such an arrangement separate power and actuator arrangements are necessary to operate the flood bar and the squeegee up and down in a chopping fashion, and to cause them to move back and forth on the print screen. The required duplication of structure for separate operation of the two devices is complex to manufacture and thus entails a great deal of expense.
At the opposite end of the cost spectrum is the older method of flooding and scraping or shaving the ink on the screen. One way of doing this is by an arrangement in which two squeegees are mounted on the same rigid arm which is formed so as to have a side view appearance of an inverted "Y". This structure is sometimes referred to as a "flip-flop" squeegee because it is movable in a back and forth manner so that one blade is used to spread or "flood" the ink across the print screen and then, after flipping to the second position, the second blade is used to scrape the excess ink away, forcing some of the ink down into open spaces in the screen in the usual screen printing manner.
The drawback with known flip-flop double squeegee applicators is that, although less expensive because of combined operating structure, they tend to produce an inferior product by smearing the print design. This is a result, at least in part, of two squeegees being used and the inability to obtain precise control thereof.
Thus, in the present invention it was desired to use a combined squeegee and flood bar (or "coating blade") mounted on the same "Y" structure for use in a flip-flop fashion. However, a great deal of difficulty is encountered in making such a device which will function adequately. The problem is that replacing one squeegee with a flood bar results in inadequate scraping of excess ink, and thus poor print quality. The applicants have discovered that the key constraint in achieving satisfactory shaving of the ink is the squeegee blade angle. Further, there is a particular blade angle which is critical for appropriate scraping or ("shaving") of the excess ink from the screen, while still having inexpensive, combined mounting and operation features.
Thus, it is among the several objects of the present invention to provide a mid-priced, multi-head, carousel-style textile printing apparatus which provides high quality prints, which is highly automated for improved speed of operation over fully manual models, and which is operable by only one or two individuals for improved efficiency of the overall printing operation, as well as reduction of operator fatique, yet is constructed so as to be capable of manufacture at a significantly lower cost than known, fully automated, high-speed, multi-head carousel textile printing apparatuses.
It is also among the objects of the present invention, having the features indicated that the new printing apparatus have precisely coordinated simultaneous lifting and lowering of all print heads thereon, while also providing for manual control of carousel movement for economy of manufacture, as well as for versatility and completeness of use, and further providing that the carousel stopping, head registration, and lifting of each print head from its printing position over a corresponding platen all be precisely and simultaneously controlled by a single operator with readily accessible controls which are positioned and designed for facile access and operation.
It is further among the objects of the present invention to provide an automated textile printing apparatus having the above-mentioned features which is of relatively simple mechanical construction for economy of manufacture and ease of operation, while at the same time requiring a minimal amount of maintenance which, when necessary, is simply accomplished.
Accordingly, in furtherance of the above objects, the invention is, briefly, a screen printing apparatus having simultaneously movable multiple print heads made movable by a single fluid cylinder. The apparatus has multiple printing platens and structure for indexing and simultaneously registering the multiple platens into printing position, and combined flood bar/squeegee ink applicators which are capable of simultaneously shifting of operational positions, and provide a high quality printed image on the goods printed thereby.
The invention is also, briefly, for use in combination with a multi-head type textile printing apparatus, a mechanism for effecting simultaneous lifting and lowering of all print heads. The printing apparatus has a plurality of print heads extending outwardly from the apparatus, each one of the plurality of print heads having an inner end projecting toward a vertical axis of the apparatus and each one of the plurality of print heads being pivotally mounted on the apparatus at a point on the print heads outward from the inner end of the corresponding print head, to thereby permit upward and downward pivotal motion of the print head. The mechanism for effecting simultaneous lifting and lowering includes structure for contacting the inner end of each one of the plurality of print heads. The structure for contacting is vertically movably mounted on the apparatus above the inner end of each one of the plurality of print heads and in sliding contact with the inner ends. The mechanism also includes structure for vertically movably mounting the structure for contacting connected thereto in such manner as to be vertically movable along the vertical axis of the apparatus. The mechanism also includes structure for effecting vertical movement of the means for vertically movably mounting the structure for contacting, to thereby cause lifting of each one of the plurality of print heads upon downward vertical movement of the structure for effecting vertical movement and lowering of each one of the plurality of print heads upon upward vertical movement of the structure for effecting vertical movement.
The invention is also, briefly, for use in combination with a carousel-type multi-head textile printing apparatus, a mechanism for effecting simultaneous indexing and registration of all printing platens on the apparatus. The printing apparatus has a plurality of print heads extending radially outwardly from the apparatus for simultaneous printing of a plurality of work pieces and a plurality of printing platens, a plurality of spaced apart rigid spokes extending radially outwardly from the printing apparatus in such manner that all of the rigid spokes are simultaneously rotatable around the apparatus in a horizontal plane, each one of the plurality of rigid spokes having one of the plurality of printing platens mounted thereon, the plurality of rigid spokes being spaced at intervals around the apparatus so as to be capable of alignment of substantially each one of the platens beneath a corresponding one of the plurality of print heads. And, the mechanism for effecting simultaneous indexing and registration of printing platens on the apparatus includes a contact rollably mounted to and extending beneath each one of the plurality of rigid spokes of the apparatus, a vertically movable stop fixed on the apparatus and positioned so as to contact a next one of the contacts upon rotational movement of the plurality of rigid spokes. The stop is adapted for receiving a contact which comes into contact therewith, to thereby rotationally lock the plurality of rigid spokes to precisely register the plurality of print heads above corresponding printing platens. The stop is further adapted for release of a contact which has been received thereby to permit an operator of the apparatus to move the plurality of rigid spokes rotationally around the apparatus so that the contact on another one of the plurality of rigid spokes can come into contact with the stop, locking the associated one of the rigid spokes, to thereby index the apparatus to another printing position and register the platen for the other printing position precisely beneath a selected one of the plurality of printing heads for printing of a work piece on the platen.
The invention is also, briefly, for use in combination with a textile printing apparatus, a mechanism for coordinated operation of a flood bar and a squeegee. The printing apparatus has at least one print head for extending over a work piece of printing thereof, and at least one platen for supporting a work piece beneath the print head during the printing operation. And, the mechanism for coordinated operation of a flood bar and a squeegee includes an elongated flood bar, an elongated squeegee, a carriage movably mounted to the at least one print head for travel therebeneath of the carriage above the work piece for printing thereof, and structure for causing the carriage to move. Also included in the mechanism is a mounting strip adapted for mounting the flood bar and the squeegee thereon, the mounting strip having an angle formed therein so that the strip is bent along the entire length thereof, the flood bar being connected to the mounting strip on one side of the bend and the squeegee being connected to the mounting strip on the other side of the bend. The strip is pivotally connected to the carriage. And the mechanism also includes structure for causing the mounting strip to pivot connected to the mounting strip, to thereby affect which of the flood bar and the squeegee is in operating position for performing the particular function thereof with regard to printing of the work piece.
Other objects will be in part apparent and in part pointed out hereinbelow.